![\"\"](\"https:\/\/www.europesays.com\/uk\/wp-content\/uploads\/2025\/08\/Kaiuroo-red-Brahman-21-June-2021.jpg\")
<\/p>\n<\/p>\n
FERTILITY tends to be a catch-all term used in the beef industry. Producers and industry observers will often refer to fertility in general, while in practice there are several key areas that combine to ultimately determine how many calves will be born and raised to weaning age each year.<\/p>\n
The risk when referring to fertility as a general term can be to cause confusion among beef breeders around the priority of traits to measure or to select for; or where to focus management and selection decisions.<\/p>\n
In many cases, beef breeders wanting to lift the number of calves born each year, as well as the number that are weaned, need to work backwards, considering the separate factors that contribute to these numbers.<\/p>\n
There has been much research conducted in beef production systems which has proven that nutrition, body condition and seasonal conditions heavily influence conception rates, let alone weaning rates.<\/p>\n
While management decisions play a significant role in these factors, genetic selection also is a critical area for all beef breeders to consider. However there has often been levels of concern \u2013 particularly in northern production systems \u2013 that the genetics required for more challenging environments need to be considered differently than in other parts of the country.<\/p>\n
Research conducted by James Copley, Ben Hayes, Elizabeth Ross, Geoffry Fordyce, Ben Wood<\/strong>\u00a0and Bailey Engle<\/strong> (University of Queensland\/QAAFI) with collaborators from Black Box Co, NABRC, and UQ Vet Science, has been published which presents some interesting findings, particularly for producers asking if animals with superior fertility breeding values in one environment would rank the same in another.<\/p>\n The research conducted across 54 herds recorded data from 21,000 heifer and cow records and specifically examined three fertility indicators:<\/p>\n In addition, the research also considered two environmental factors. The first was\u00a0nutrition, represented by the average daily weight gain (ADWG) of each herd, grouped into quartiles from the lowest ADWG (1) which was considered the harshest level of nutrition to the highest ADWG (4) or most favourable nutrition.<\/p>\n The second factor considered was\u00a0heat load, with the research using temperature-humidity index (THI)\u00a0where animals were allocated to one of three groups with One being the longest exposure to heat load (harshest)\u00a0through to\u00a0Three being the shortest exposure (most favourable).<\/p>\n Although previous research has shown that fertility traits are heritable and can be improved through selection, this study is the first to examine more closely if northern herds need\u00a0different evaluations for the range of challenging environments, most notably nutrition and heat.<\/p>\n<\/blockquote>\n Although previous research has shown that fertility traits are heritable and can be improved through selection, this study is the first to examine more closely if northern herds need\u00a0different evaluations for the range of challenging environments, most notably nutrition and heat.<\/p>\n For heat, there was\u00a0only one marginal case: the genetic correlation for first pregnancy between moderate and high heat-load environments fell just below the threshold expected by chance. Even this was weak and not consistent across comparisons. In other words, the same animals ranked highly for fertility regardless of whether they were in harsher nutritional or hotter environments.<\/p>\n The project results have also included heritability estimates which have shown that the Corpus Luteum Presence at 600 days has a moderate heritability (0.27\u20130.30), making it a practical early selection trait for producers to adopt.\u00a0 For the other fertility indicators, first pregnancy had low to moderate heritability (around 0.15), while second pregnancy at 3.5 years was also\u00a0low (0.08\u20130.18).\u00a0 Although this is a low figure there is slightly enough genetic contribution to respond to selection over time.<\/p>\n More importantly for this research has demonstrated, particularly for northern beef breeders, that the current fertility evaluations are suitable to support selection decisions, even in the more challenging environments.<\/p>\n Useful suggestions<\/p>\n However, while genetic selection decisions are supported by current systems, the research offers some useful suggestions for producers who are striving to make improvements within their breeding programs.<\/p>\n A key outcome is the value of measuring and selecting on early fertility indicators, particularly CL presence in heifers. As a moderately heritable trait, measurement allows producers to identify females more likely to conceive early and consistently. Retaining heifers that cycle earlier translates into higher lifetime productivity.<\/p>\n For sire selection, these results highlight that there is no need to restrict sire selection only to bulls evaluated in a specific environment. A bull with strong fertility breeding values should rank similarly across the north.<\/p>\n The key is ensuring those sires are still assessed for temperament, and structure and breed suitability for specific breeding objectives.<\/p>\n For seedstock breeders, the project offers confidence that fertility data being presented is relevant to clients across the north, without having to split their selection or marketing by region.<\/p>\n While genetic rankings were stable across environments, nutrition and heat load still directly affected outcomes. Pregnancy rates improved with better average daily gains, emphasising the importance of feed management and body condition at joining.<\/p>\n Managing heat load as much as possible through shade, water and paddock design remains important for welfare and feed intake, even if it doesn\u2019t alter genetic rankings for fertility.<\/p>\n Producers who continue to focus on fertility breeding values, measure early indicators in heifers, and manage nutrition around joining will see improvements in their breeding outcomes.<\/p>\n These results add to the confidence many producers should feel when assessing genetic information at selection that the genetics for fertility in northern beef herds are robust enough to work across environments without the need for separate evaluations.<\/p>\n \u00a0<\/p>\n Alastair Rayner<\/p>\n Alastair Rayner\u00a0is Principal of RaynerAg and an Extension & Engagement Consultant with the Agricultural Business Research Institute (ABRI). He has over 28 years\u2019 experience advising beef producers and graziers across Australia. Alastair can be contacted here or through his website:\u00a0www.raynerag.com.au<\/a><\/p>\n \u00a0<\/p>\n \u00a0<\/p>\n \u00a0<\/p>\n \u00a0<\/p>\n \u00a0<\/p>\n \u00a0<\/p>\n \u00a0<\/p>\n \u00a0<\/p>\n \u00a0<\/p>\n \u00a0<\/p>\n \u00a0<\/p>\n \u00a0<\/p>\n \u00a0<\/p>\n \u00a0<\/p>\n \u00a0<\/p>\n","protected":false},"excerpt":{"rendered":"FERTILITY tends to be a catch-all term used in the beef industry. Producers and industry observers will often…\n","protected":false},"author":2,"featured_media":357057,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3846],"tags":[267,70,16,15],"class_list":{"0":"post-357056","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-genetics","8":"tag-genetics","9":"tag-science","10":"tag-uk","11":"tag-united-kingdom"},"share_on_mastodon":{"url":"https:\/\/pubeurope.com\/@uk\/115056008731654433","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/posts\/357056","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/comments?post=357056"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/posts\/357056\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/media\/357057"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/media?parent=357056"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/categories?post=357056"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/tags?post=357056"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}\n
\n
![\"\"](\"https:\/\/www.europesays.com\/uk\/wp-content\/uploads\/2025\/08\/Droughtmaster-Australia-Floating-MREC-Jul25.jpg\")
<\/a>The results demonstrated that across the four levels of nutrition (assessed in ADWG) there was\u00a0no evidence of significant Genetic \u00d7Environment (GxE) impact\u00a0for any of the three fertility traits.<\/p>\n![\"\"](\"https:\/\/www.europesays.com\/uk\/wp-content\/uploads\/2025\/06\/unnamed-66-1-e1750749721925.jpg\")
<\/p>\n